U.S. patent application number 10/590003 was filed with the patent office on 2011-07-21 for drive system for a vehicle.
Invention is credited to Rainer Gugei, Nicolai Tarasinski.
Application Number | 20110178660 10/590003 |
Document ID | / |
Family ID | 34961194 |
Filed Date | 2011-07-21 |
United States Patent
Application |
20110178660 |
Kind Code |
A1 |
Tarasinski; Nicolai ; et
al. |
July 21, 2011 |
DRIVE SYSTEM FOR A VEHICLE
Abstract
The invention relates to a drive system for a vehicle, in
particular, for an agricultural or industrial commercial vehicle.
The drive system (10) comprises a first and a second drive module
(12, 14), a first and a second branch (22, 24), at least one
controller (16) and at least one output interface (30). The first
drive module (12) may be switched to the first branch (22). The
second drive module (14) may be switched to the second branch (24).
The first branch (22) and/or the second branch (24) is(are)
reversibly connectable to the output interface (30). The drive
modules (12, 14) may be controlled with at least one controller
(16) such that the drive modules (12, 14) can provide a step-free
and independent given power. Said drive system comprises a greater
range than conventionally available and at least substantially
avoids inconvenient switching processes.
Inventors: |
Tarasinski; Nicolai;
(Frankenthal, DE) ; Gugei; Rainer; (Mannheim,
DE) |
Family ID: |
34961194 |
Appl. No.: |
10/590003 |
Filed: |
March 2, 2005 |
PCT Filed: |
March 2, 2005 |
PCT NO: |
PCT/EP2005/050926 |
371 Date: |
June 13, 2007 |
Current U.S.
Class: |
701/22 ;
180/65.265; 701/101; 701/54; 701/99; 903/930 |
Current CPC
Class: |
B60L 15/20 20130101;
Y02T 10/62 20130101; B60L 2200/40 20130101; Y02P 90/60 20151101;
Y02T 10/6221 20130101; B60K 6/48 20130101; Y02T 10/72 20130101;
Y02T 10/645 20130101; Y02T 10/64 20130101; Y02T 10/7275
20130101 |
Class at
Publication: |
701/22 ; 701/99;
701/101; 701/54; 180/65.265; 903/930 |
International
Class: |
B60W 20/00 20060101
B60W020/00; B60W 10/08 20060101 B60W010/08; B60W 10/06 20060101
B60W010/06; B60W 10/10 20060101 B60W010/10 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 15, 2004 |
DE |
10 2004 012 767.0 |
Claims
1. Drive system for a vehicle, especially for an agricultural or
industrial utility vehicle, with a first and a second drive module
(12, 14), a first and a second branch (22, 24), at least one
controller (16), and at least one output interface (30), wherein
the first drive module (12) can be connected to the first branch
(22), wherein the second drive module (14) can be connected to the
second branch (24), wherein the first branch (22) and/or the second
branch (24) can be connected reversibly to the output interface
(30), and wherein the drive modules (12, 14) can be controlled with
at least one controller (16), such that the drive modules (12, 14)
can output a given power--especially a rotational
speed--continuously and independently of each other.
2. Drive system according to claim 1, wherein one drive module (12,
14) has an internal combustion engine, especially a diesel
engine.
3. Drive system according to claim 1 or 2, wherein one drive module
(12, 14) has an energy source generating electric current and a
mechanical conversion stage.
4. Drive system according to claim 1, wherein one input interface
(38) and at least one converter module (44) is provided, wherein
the input interface (38) can be connected to an energy source
(36)--preferably constructed in the form of an internal combustion
engine of the vehicle--wherein energy generated by the energy
source (36) can be distributed via the input interface (38) to the
first and to the second branch (22, 24), wherein the converter
module (44) is connected to at least one drive module (12, 14), and
wherein the converter module (44) can be connected to the input
interface (38).
5. Drive system according to claim 4, wherein--preferably
controlled by the controller (16)--energy can be distributed or
transported arbitrarily between the converter module (44) and at
least one drive module (12, 14).
6. Drive system according to claim 4 or 5, wherein the energy
source (36) generates mechanical and/or electrical energy.
7. Drive system according to one of claims 4-6, wherein a
controller is provided, which controls the energy source (36),
whereby preferably the energy generated by the energy source (36)
is variable.
8. Drive system according to one of claims 4-7, wherein the energy
source (36) includes an internal combustion engine, especially a
diesel engine, a generator driven by an internal combustion engine,
a fuel cell, and/or an electrical storage device--for example, an
accumulator, a capacitor, or a battery.
9. Drive system according to one of claims 1-8, wherein another
output interface (66) is provided, which can be connected
reversibly to one of the two branches (22, 24), preferably to the
second branch (24).
10. Drive system according to one of claims 4-9, wherein mechanical
and/or electrical energy can be transmitted via the input interface
(38), the output interface (30), and/or the other output interface
(66).
11. Drive system according to one of claims 1-10, wherein a shaft
is provided for transmitting mechanical energy.
12. Drive system according to one of claims 1-11, wherein the first
and/or the second branch (22, 24) and/or the output interface (30)
each has at least one mechanical gear stage, with which preferably
a rotational speed reduction and/or a rotational speed reversal can
be achieved.
13. Drive system according to claim 12, wherein the mechanical gear
stage has at least one spur gear stage and/or a planetary gear
unit.
14. Drive system according to one of claims 1-13, wherein a
reversible connection between an output interface (30) and a branch
(22, 24) can be established with the aid of a positive-fit coupling
(52, 64, 82, 88).
15. Drive system according to claim 14, wherein the positive-fit
coupling (52, 64, 82, 88) can be shifted by means of an
electrically activated shift element, wherein preferably the shift
element for coupling or decoupling the reversible connection works
against a spring force.
16. Drive system according to claim 14 or 15, wherein the
positive-fit coupling (52, 64, 82, 88) works according to the
principle of a claw coupling.
17. Drive system according to one of claims 4-16, wherein a
converter module (44) receives mechanical and/or electrical
energy.
18. Drive system according to one of claims 4-17, wherein a drive
module (12, 14) outputs mechanical and/or electrical energy.
19. Drive system according to one of claims 4-18, wherein a
conversion between electrical and mechanical energy is performed
with the converter module (44) and the drive modules (12, 14).
20. Drive system according to claim 19, wherein the converter
module (44) has at least one electric machine that can be operated
as a generator.
21. Drive system according to claim 19 or 20, wherein the first and
the second drive module (12, 14) each has an electric machine that
can be operated as a motor.
22. Drive system according to one of claims 4-21, wherein a
conversion between hydraulic and mechanical energy is performed
with the converter module (44) and the drive modules (12, 14).
23. Drive system according to claim 22, wherein the converter
module (44) has at least one mechanically driven, preferably
adjustable, hydropump.
24. Drive system according to claim 22 or 23, wherein the first and
the second drive module (14) each has a preferably adjustable
hydromotor.
25. Drive system according to one of claims 4-24, wherein
mechanical energy can be converted with the converter module (44)
and the drive modules (12, 14).
26. Drive system according to claim 25, wherein the converter
module (44) has an input shaft of a belt gear, a friction gear, or
a chain converter.
27. Drive system according to claim 26, wherein the first and the
second drive module (12, 14) each has at least one output shaft of
the corresponding gear.
28. Drive system according to one of claims 4-27, wherein the input
interface (38) is mechanically coupled to the first and the second
branch (22, 24).
29. Drive system according to claim 28, wherein the converter
module (44) is allocated to the energy source (36) or has an
electric machine driven by the energy source (36) and operating as
a generator.
30. Drive system according to claim 28 or 29, wherein the first and
the second drive module (12, 14) each has an electric machine
operating as a motor.
31. Drive system according to one of claims 4-27, wherein the input
interface (36) is electrically or hydraulically coupled to one of
the two branches (22) and the input interface (36) is mechanically
coupled to the other of the two branches (24).
32. Drive system according to claim 31, wherein the converter
module (44) has an electric machine (preferably always) driven
mechanically by the energy source (36) and operating as a
generator.
33. Drive system according to claim 31 or 32, wherein the first
branch (22) can be driven mechanically with the first drive module
(12).
34. Drive system according to one of claims 31-33, wherein the
second drive module (14) can be connected to the second branch (24)
or has a power-diverted arrangement to this branch, preferably via
a planetary gear (54).
35. Drive system according to one of claims 31-34, wherein a brake
(71), preferably a friction brake, with which at least one part of
the second branch (24) can be stopped relative to a housing of the
drive system (10), is provided in the second branch (24).
36. Drive system according to one of claims 31-35, wherein the
converter module (44) and/or the first drive module (12) are/is
arranged essentially coaxial to the input interface (36).
37. Drive system according to one of claims 31-36, wherein the
second drive module (14) is arranged essentially coaxial to the
output interface (30).
38. Drive system according to claim 36 or 37, wherein the first
drive module (12) is arranged spatially downstream of the converter
module (44) with reference to the input interface (38) and wherein
preferably the first drive module (12) is arranged downstream of
the second drive module (14) with reference to the input interface
(38).
39. Drive system according to one of claims 1-48, wherein of the
converter module (44) and/or the drive modules (12, 14), at least
two modules (44, 14)--preferably all three modules (44, 12,
14)--are arranged essentially coaxial to each other.
40. Drive system according to one of claims 1-39, wherein the first
branch (22) and the second branch (24) can each be connected
reversibly to the output interface (30) via a shiftable multi-step
transmission.
41. Drive system according to one of claims 1-40, wherein the
second branch (24) can be connected reversibly to the other output
interface (66) via a shiftable multi-step transmission.
42. Drive system according to claim 40 or 41, wherein at least two
different transmission ratios can be realized with the shiftable
multi-step transmission.
43. Drive system according to one of claims 1-42, wherein the
output interface (30) can be connected to a traction drive and/or
that the other output interface (66) can be connected to a power
take-off (PTO).
44. Drive system according to one of claims 1-43, wherein it is
possible to shift between the two branches (22, 24) under
loading.
45. Drive system according to one of claims 1-44, wherein at least
one sensor is provided, with which the operating state of at least
one component of the drive system (10) can be detected and can be
fed to the controller (16), so that preferably the possible shift
states of the drive system (10) can be detected redundantly.
46. Drive system according to one of claims 1-45, wherein in a
first shift state, the first branch (22) is connected to the output
interface (30) and wherein the first drive module (12) is connected
to the first branch (22).
47. Drive system according to one of claims 1-46, wherein the
second branch (24) is connected to the other output interface (66)
and wherein the second drive module (14) is connected to the second
branch (24).
48. Drive system according to one of claims 1-47, wherein in a
second shift state, the first and the second branch (22, 24) are
connected to the output interface (30) and wherein preferably the
rotational speeds of the two drive modules (12, 14) are tuned or
synchronized to the rotational speed of the output interface
(30).
49. Drive system according to one of claims 1-48, wherein in a
third shift state, the second branch (24) is connected to the
output interface (30) and that preferably the second branch (24) is
connected to the other output interface (66).
50. Vehicle, especially an agricultural or industrial utility
vehicle, preferably a tractor, which has a drive system (10)
according to one of claims 1-49.
51. Drive module and/or converter module and/or controller a drive
system (10) according to one of claims 1-49.
Description
[0001] The invention relates to a drive system for a vehicle,
particularly for an agricultural or industrial utility vehicle. The
present invention further relates to a vehicle with such a drive
system, as well as to a drive module and/or a converter module
and/or a controller for such a drive system.
[0002] Electric motors are increasingly being used to drive
vehicles, which draw their energy from internal combustion
engine-driven generators, batteries, or fuel cells. To achieve a
higher spread, in many cases shiftable gear stages are arranged
after the electric motors, but usually the power transfer is
realized without shifting stages. The term "spread" is understood
to be the speed range over which nominal power can be reached at
the power take-off.
[0003] For road and rail vehicles, the state-of-the-art procedure
currently described usually has been sufficient for achieving the
desired driving power. Here, the spread lies on the order of 5-10.
The lowest speed at which nominal power is achieved frequently lies
over 20 km/h. For agricultural utility vehicles and especially for
tractors, this spread is not sufficient. Values over 15 are
necessary to cover the driving tasks of a tractor. The lowest speed
at which nominal power is achieved lies in the vicinity of 3 km/h.
Due to the low absolute speed and high traction force of tractors,
shifting processes, with which it must be shifted into a different
speed range for a similar traction force, are very uncomfortable
due to the transmission jump in the drive system. The continuously
variable power shift gears frequently used in tractors typically
have two branches, by means of which the torque of the drive module
or the energy source is selectively transmitted to the traction
drive. When shifting to a different speed range, torque is also
transmitted from the drive module to the traction drive during the
shifting process (power shift gear). If a shifting process is
performed, one branch of the gear is separated or decoupled from
the traction drive, while the other branch of the gear is coupled
and thus connected to the traction drive. A shifting process is
subject to constraining conditions, because the rotational speeds
of the two branches must essentially match at the time of the
shifting process.
[0004] Moreover, in contrast to road and rail vehicles, tractors,
in addition to the traction drive, are usually equipped with one or
more additional mechanical power take-off devices for attachments,
a so-called power take-off (PTO).
[0005] In the following, the term "branch" designates a part of a
drive system or a gear, which can transmit mechanical torque, or,
very generally, energy. Thus, it can involve a shaft and rotating
transmission elements connected to this shaft and/or shifting
stages.
[0006] Therefore, the present invention is based on the task of
specifying and improving a drive system of the type named above,
through which the previously mentioned problems are overcome. In
particular, a drive system shall be specified, which features a
spread that is expanded relative to the state of the art and which
at least essentially prevents uncomfortable shifting processes.
[0007] Corresponding tasks form the basis for the vehicle named
above with such a drive system, as well as for the drive module
and/or the converter module and/or the controller for such a drive
system.
[0008] The task is realized according to the invention in terms of
the drive system by the teaching of Claim 1. Additional
advantageous configurations and improvements of the invention
emerge from the subordinate claims.
[0009] According to the invention, the drive system comprises a
first and a second drive module, a first and a second branch, at
least one controller, and at least one output interface. The first
drive module can be connected to the first branch. The second drive
module can be connected to the second branch. The first branch
and/or the second branch can be connected reversibly to the output
interface. The drive modules can be controlled with at least one
controller, so that the drive modules can output a given power or
energy continuously and independently of each other.
[0010] One output interface could be, for example, a shaft, which
can be coupled to a traction drive of a vehicle and by means of
which, for example, mechanical torque can be transmitted to the
drive of the vehicle.
[0011] The drive system according to the invention has two
branches--especially for continuous shifting processes under
loading--between which the system can be shifted back and forth but
which can also be connected simultaneously to the output shaft. The
drive modules can be controlled by the controller independently of
each other for the output of a given power; for example, in the
form of a mechanical torque or very generally in the form of
energy. Thus, a state can be created in the drive system, in which
the mechanical rotational speeds of the two branches are each
adapted to that of the output interface, so that a synchronous
shifting process is possible, if, for example, the connection of
the first branch to the output interface is broken and the
connection of the second branch to the output interface is
established. With the drive system according to the invention, the
state is also provided that both the first and also the second
branch are connected to the output interface, whereby the
preferably mechanical power output by the two drive modules can be
added. Each of the two branches could have fixed speed and
transmission ranges in which they are used.
[0012] Due to the independent control of the two drive modules, it
is possible to design the speed ranges of the two branches, such
that these ranges overlap. Thus, in the overlapping ranges,
advantageously one or both branches can be arbitrarily connected to
or separated from the output interface. Even if both branches are
connected to the output interface, the transmission between the
first branch and the output interface and the second branch and the
output interface can be adjusted; thus, in contrast to conventional
multi-step or multi-range transmissions, there is not a
constraining condition for the existing mechanical transmission.
Accordingly, a shifting process of the drive system according to
the invention requires only the coupling or decoupling (or
connection or disconnection) of one branch to the output interface,
for example, such that a corresponding shift coupling between the
branch and the output interface is activated. Finally, two shifting
processes--for example, the connection of one branch to the output
interface and the disconnection of the other branch from the output
interface--can lie arbitrarily far apart from each other in time,
whereby overall a nearly jerk-free shifting of the speed ranges of
the drive system is possible.
[0013] In principle, it could be provided that a drive module has
an internal combustion engine. Especially preferred, a diesel
engine would be used in this case. Diesel engines are regularly
used, especially for agricultural utility vehicles, due to their
multiple control possibilities and their high efficiency. It would
be conceivable, for example, that one drive system has two diesel
engines.
[0014] Alternatively or additionally, a drive module could have an
energy source, which generates electric current, for example, a
fuel cell. This drive module could further have a mechanical
conversion stage, with which the electric current is converted into
mechanical torque.
[0015] The provision of two energy sources, which can be controlled
independently of each other and which can each be connected to the
first or to the second branch, is associated in an especially
advantageous way with great flexibility in terms of the control
possibilities and the operating states of the drive system, but can
result in increased production costs. The basic concept of the
drive system according to the invention can also be used when only
one energy source is provided for a vehicle. In such a case, the
drive system also has an input interface and at least one converter
module. The input interface can be connected to an energy source,
preferably embodied in the form of an internal combustion engine of
a vehicle. Energy generated by the energy source or delivered power
can be distributed to the first and to the second branch via the
input interface. The converter module is connected to the drive
modules. The converter module can be connected to the input
interface. In the present sense, an input interface is understood
to be an interface, which receives energy generated by the energy
source and supplies it to the drive system. The input interface
could be constructed in the form of a shaft, if the energy source
is embodied in the form of an internal combustion engine and
provides mechanical torque.
[0016] So that the drive modules can output a given power
independently of each other or can be operated with a given torque,
energy or power can be distributed or transported arbitrarily
between the converter module and the drive modules. Such an
energy/power transport is preferably controlled by the controller.
If the converter module has an electric generator and the two drive
modules each has an electric machine, such an energy transport
could be realized with the aid of a power electronics
controller.
[0017] Preferably, an energy source is used, which generates
mechanical and/or electrical energy. For controlling the energy
source, a separate controller could be provided. In this way, the
energy generated by the energy source is variable; thus, it can be
adapted to the corresponding operating state of the drive system or
a vehicle.
[0018] The energy source could have an internal combustion engine,
especially a diesel engine. Furthermore, the energy source could
include a generator driven by an internal combustion engine and/or
a fuel cell and/or an electric storage device, for example, an
accumulator, a capacitor, or a battery.
[0019] In an especially preferred embodiment, another output
interface is provided. This additional output interface could be
connected, in principle, reversibly to the first or to the second
branch; preferably, the drive system is embodied such that the
additional output interface can be connected reversibly to the
second branch. The additional output interface could involve a
power take-off (PTO) for transmitting mechanical torque, which is
typically provided on tractors for mechanically driving work
equipment.
[0020] Very generally, mechanical and/or electrical energy can be
transmitted via the input interface, the output interface, and/or
the additional output interface. If mechanical energy, for example,
in the form of torque, is to be transmitted via an interface, a
shaft could be provided for this purpose. Electrical energy could
be transmitted inductively or with the aid of sliding contacts by
means of correspondingly designed electrical lines.
[0021] Preferably the first and/or the second branch and/or the
output interface each has at least one mechanical gear stage. With
such a gear stage, a rotational speed reduction and/or a rotational
speed reversal could be achieved. Thus, the flexibility of a branch
can be further increased and the spread of the drive system
according to the invention can be increased still more. In detail,
the mechanical gear stage could have at least one spur gear stage
and/or one planetary gear unit.
[0022] Especially preferred, a reversible connection between an
output interface and a branch is produced with the aid of a
positive-fit coupling. Synchronization, which is necessary for this
purpose, between the rotational speeds of a shaft allocated to the
output interface and a shaft allocated to a corresponding branch
can be achieved with the aid of the two drive modules, which can be
controlled independently of each other. The positive-fit coupling
could be shifted by means of an electrically controllable shifting
element, but a mechanical or hydraulic activation of the shifting
element could also be conceivable. Preferably, the shifting element
for coupling for decoupling the reversible connection works against
a spring force, so that only an actuator--namely, for example, the
electrically activated shifting element--is to be provided. The
positive-fit coupling could work according to the principle of a
claw coupling.
[0023] In principle, between the converter module and the two drive
modules, an energy or power transport could be performed, which
enables part or all of the energy/power provided by the energy
source to be distributed arbitrarily from the converter module to
the two drive modules. Here, it may be necessary to convert the
energy before distributing it; examples for this purpose are given
below. Therefore, it is to be provided, in particular, that a
converter module receives mechanical and/or electrical energy.
Additionally or alternatively, one drive module could output
mechanical and/or electrical energy.
[0024] In an especially preferred embodiment, a conversion between
electrical and mechanical energy is performed with the converter
module and the drive modules. For this purpose, the converter
module could have at least one electric machine that can be
operated as a generator. Furthermore, the first and the second
drive modules could each has an electric machine that could be
operated as a motor. Thus, for example, the mechanical energy
generated by the energy source is fed at least partially to the
converter module, which converts this energy into electric current.
The electric current is fed to the drive modules, which, on its
side, converts this electrical energy back into mechanical
torque.
[0025] With the converter module and the drive modules, a
conversion between hydraulic and mechanical energy could also take
place. For this purpose, the converter module could have at least
one mechanical drive hydropump. The hydropump is preferably
adjustable, so that the amount and thus the pressure of the
hydraulic fluid generated by the hydropump is variable. With the
hydropump, the mechanical energy is converted into hydrostatic
energy. The hydrostatic energy can then be converted back into
mechanical energy by a drive module, if the first and/or the second
drive module each has a hydromotor. Preferably, such a hydromotor
is also adjustable, i.e., the hydromotor can be operated at
different rotational speeds for a constant pressure of the
hydraulic fluid.
[0026] As another example, a purely mechanical conversion between
the converter module and the drive modules is conceivable. For this
purpose, the converter module could have an input shaft of a gear,
for example, a loop gear, a friction gear, or a chain converter.
The first and the second drive module could each has at least one
output shaft of the corresponding gear.
[0027] Very generally, a plurality of embodiments according to the
invention are conceivable, wherein the drive system of Claim 1 can
be improved with the components, arrangements of components, as
well as their functioning, disclosed in the scope of this patent
application. Here, the drive system according to the invention can
be optimized for any type and can be performed by vehicles, for
example, for construction machines, combines, or field choppers.
Especially preferred embodiments, which could be suitable
especially for tractors, are described below.
[0028] According to the first embodiment, the input interface is
mechanically coupled to the first and to the second branch. The
converter module is either allocated to the energy source or the
converter module has an electric machine driven by the energy
source and operating as a generator. Accordingly, the energy source
directly provides electrical energy or is embodied, for example, in
the form of an internal combustion engine, which drives the
converter module mechanically, so that the converter module--the
electric machine operating as a generator--generates electric
current. The first and the second drive module each has an electric
machine operating as a motor. Here, one of the two drive modules is
always connected to its allocated branch.
[0029] According to a second embodiment, the input interface is
mechanically coupled to one of the two branches. If this branch is
connected to the output interface, preferably only mechanical
energy is transmitted via this branch. Connection to the drive
module allocated to this branch would also be conceivable. The
input interface is electrically or hydraulically coupled to the
other branch. Here, the converter module has, e.g., an electric
machine driven mechanically by the energy source and operating as a
generator. The electric machine operating as a generator is then
preferably always driven mechanically by the energy source.
[0030] The first branch can be driven mechanically by the first
drive module. The second drive module can be connected to the
second branch or power diverted to this branch that could be
realized with the aid of a planetary gear. In the second branch, a
brake is provided, with which at least part of the second branch
can be stopped relative to a housing of the drive system. The brake
could involve a friction brake. Thus, for example, the mechanical
torque transmitted by the input interface could be fed to a sun
wheel of a planetary gear. The second drive module could be
connected to the planet carrier of the planetary gear. The part of
the second branch that can be brought into connection with the
output interface could be connected to the ring gear of the
planetary gear. This part of the second branch could be stopped
with the brake, so that for a stopped brake, and thus a stopped
ring gear of the planetary gear, the second drive module is driven
directly. The electrical energy generated by the converter module
and the second drive module can be fed to the first drive module,
which can be connected, on its side, to the output interface of the
drive system. In this operating state, only the transmission of
electrical power to the output interface is performed.
[0031] A compact construction can be achieved especially in this
embodiment when the converter module and/or the first drive module
are/is arranged essentially coaxial to the input interface. The
same applies for the case that the second drive module is arranged
essentially coaxial to the output interface. All three
modules--i.e., the converter module and the two drive modules--are
especially preferably arranged coaxial to the input interface.
[0032] In structural terms, it is advantageous if the first drive
module is arranged spatially downstream of the converter module
relative to the input interface. Optionally, it is possible to
combine the converter module and the first drive module into one
housing. Likewise, the first drive module could be downstream of
the second drive module relative to the input interface. Overall, a
sequence of components is preferred, which, viewed outwards from
the input interface, is arranged as follows: converter module,
second drive module, first drive module. Thus, of the converter
module and/or the drive modules, preferably at least two modules
are arranged essentially coaxial to each other.
[0033] Preferably, the first branch and the second branch are each
connected reversibly to the output interface via a shiftable
multi-step transmission. The second branch can be connected
reversibly to the other output interface via a shiftable multi-step
transmission. The shiftable multi-step transmission could be
embodied such that at least two different transmission ratios can
be realized. Here, the torque applied to one branch can be
transmitted with different rotational speeds and/or rotational
directions to the output interface.
[0034] The output interface of the drive system according to the
invention could be connected in a vehicle to a traction drive or
can be connected in this way. The other output interface could be
connected to a power take-off (PTO), so that mechanical torque can
also be transmitted--for example, to work equipment coupled to a
tractor--via the second output interface.
[0035] Especially preferred, the drive system is designed such that
shifting between the two branches is possible under loading, that
is, mechanical torque is always transmitted to the traction drive.
Here, the drive system according to the invention is suitable
especially for tractors, because, especially when culling during an
accelerating phase, a shifting process of the drive system must be
performed under loading.
[0036] So that the drive system according to the invention can be
embodied reliably in terms of operating safety, at least one sensor
is provided, with which the operating state of at least one
component of the drive system can be detected and fed to the
controller. Thus, for example, rotational speed sensors could be
provided, which each detect the rotational speed of a shaft of a
branch. Furthermore, pressure sensors could detect the pressure of
the hydraulic fluid of the hydraulically operating drive modules.
The operating state of electrically operating components--the
converter module and/or a drive module--could be detected with
current/voltage sensors. Also, redundancy is provided in terms of
the possible shift or operating states of the drive system.
[0037] Because the two branches of the drive system according to
the invention can be driven with the aid of the drive modules
continuously and completely independently of each other, in
contrast to conventional gears, the drive system according to the
invention does not necessarily have a well-defined shift state or
operating states. Instead, the drive system according to the
invention can have a plurality of different shift states, of which
a few preferred shift states are discussed below merely as
examples.
[0038] Thus, for example, in a first shift state, the first branch
is connected to the output interface and the first drive module is
coupled to the first branch. Therefore, in this shift state, the
energy delivered by the energy source--for example, in the form of
mechanical torque--is output via the first branch to the output
interface. Here, for example, a tractor equipped with the drive
system according to the invention could perform a slow forward or
reverse travel. In principle, the second branch in this shift state
has no function. However, in this shift state the second branch
could be connected to the other output interface and the second
drive module could be coupled to the second branch. Thus, in the
tractor equipped with the drive system according to the invention,
in the second shift state the power take-off could be connected and
adjustable independently in its rotational speed.
[0039] In a second shift state, the first and the second branch are
connected to the output interface. Here, the power transmitted from
the first and the second branches to the output interface are
added, so that in this shift state, a tractor equipped with the
drive system according to the invention can perform a slow forward
or reverse travel, especially for large traction-force
requirements. Here, the rotational speeds of the two drive modules
could be set to the rotational speed of the output interface or
synchronized with this speed. The other output interface--in the
example of a tractor the power take-off--is in this shift state
dependent on the traveling speed and therefore can be used as a
so-called "motion power take-off."
[0040] Thus, preferably a third shift state is further provided, in
which the second branch is connected to the output interface. In a
corresponding design or construction of the drive system according
to the invention for a tractor, in this shift state, the traveling
speed could be significantly higher and the traction force could be
significantly lower than, for example, in the first shift state. In
the third shift state, it is preferably provided that the second
branch is connected to the other output interface. For the example
of a tractor equipped with the drive system according to the
invention--here the rotational speed of the output interface; i.e.,
the traction drive--would be coupled with the rotational speed of
the other output interface; i.e., the power take-off, so that in
this shift state, a "motion power take-off" can also be
realized.
[0041] In terms of a vehicle named above, the aforementioned
problem is solved by the features of Claim 50. Here, the vehicle
according to the invention has a drive system according to one of
Claims 1-49. The vehicle could involve an agricultural or
industrial utility vehicle. Especially preferred, the vehicle
involves a tractor. Furthermore, the vehicle could involve a
combine, a field chopper, or a construction machine, for example, a
wheel loader or a backhoe loader.
[0042] With reference to the modules named above, the
aforementioned problem is solved by the features of Claim 51. Here,
the modules according to the invention involve a drive module
and/or a converter module and/or a controller for a drive system
according to one of Claims 1-49.
[0043] There are various possibilities for embodying and improving
the description of the present invention in advantageous ways. For
this purpose, on the one hand, refer to the claims subordinate to
Claim 1 and, on the other hand, refer to the following explanation
of the preferred embodiments of the invention with reference to the
drawing. In connection with the explanation of the preferred
embodiments of the invention with reference to the drawing,
generally preferred configurations and improvements of the
description are also explained. Shown in the drawing, each in a
schematic view, are
[0044] FIG. 1, a first embodiment according to the invention,
[0045] FIG. 2, a second embodiment according to the invention,
[0046] FIG. 3, a third embodiment according to the invention,
[0047] FIG. 4, a fourth embodiment according to the invention,
and
[0048] FIG. 5, a fifth embodiment, which is similar to the
embodiment from FIG. 3 and shows more details.
[0049] The same or similar assemblies are characterized in the
figures with the same reference symbols.
[0050] FIG. 1 shows a first embodiment of a drive system 10
according to the invention. The drive system 10 comprises a first
drive module 12 and a second drive module 14, which can be
controlled by the controller 16 via the lines 18, 20. The two drive
modules 12, 14 can be controlled by a controller 16 independently
of each other and can continuously output power set by the
controller 16. The drive system 10 comprises a first branch 22 and
a second branch 24, wherein the two branches in FIG. 1 are shown
merely schematically in the form of a shaft.
[0051] The drive module 12 can be connected to the first branch 22
via the schematically shown gear connection 26. The drive module 14
can be connected to the second branch 24 via the schematically
shown gear connection 28. Preferably, the gear connections 26, 28
are always connected; for example, an output shaft of the drive
modules 12, 14 is locked in rotation via a corresponding gear
connection 26, 28 to the first and to the second branch 22, 24,
respectively.
[0052] The drive system further comprises the output interface 30,
which can be connected reversibly to the first and/or to the second
branch 22, 24. Each connection is realized schematically with a
module 32, 34.
[0053] For example, the drive modules 12, 14 can each involve an
internal combustion engine embodied in the form of a diesel engine.
However, at least one of the two drive modules 12, 14 could also be
embodied in the form of a fuel cell, which initially generates
electric current, which is converted by a conversion stage (not
shown in FIG. 1) into mechanical torque.
[0054] Assuming that the two drive modules 12, 14 are always locked
in rotation with the two branches 22, 24, in principle, three shift
states of the drive system 10 are conceivable. In a first shift
state, only the drive module 12 is controlled by the controller 16,
so that the torque generated by the drive module 12 is transmitted
to the branch 22 via the gear connection 26. The first branch 22 is
connected in this shift state to the output interface 30 via the
module 32, so that the branch 22 transmits the torque to the output
interface 30. A vehicle equipped with such a drive system 10 could
be driven forwards in this shift state, for example, in a first
speed range.
[0055] In a second shift state of the drive system 10, only the
drive modules 14 are controlled by the controller 16. The second
branch 24 is connected to the output interface 30 via the module
34, so that the torque generated by the drive module 14 is
transmitted to the output interface 30 via the second branch 24. In
this shift state, the vehicle could be driven forwards at a greater
speed, for example, in a second traveling range.
[0056] In a third shift state of the drive system, both drive
modules 12, 14 are controlled by the controller 16, wherein both
the first branch 22 and also the second branch 24 are connected to
the output interface 30 via the modules 32, 34. In this shift
state, the torque generated by the two drive modules 12, 14 is
transmitted as a sum to the output interface 30. Here, the first
and the second branch 22, 24 have a fixed rotational speed ratio,
which is adapted to the rotational speed of the output interface
30. In this shift state, the vehicle could be operated under
increased load.
[0057] FIG. 2 also shows in a schematic view a second embodiment of
a drive system 10 according to the invention. In terms of the
components shown in FIG. 1, the drive system 10 shown in FIG. 2 is
comparably constructed. In this embodiment, an energy source 36 is
provided, which can be connected at the input interface 38 (shown
with dashed lines) to the drive system 10. In detail, the energy
source 36 comprises a diesel engine, which is coupled to the input
shaft 40 of the drive system 10. The diesel engine transmits
mechanical torque to the two branches 22, 24, which is realized
with the aid of the schematically shown component 42. The energy
source 36 also comprises a converter module 44, which is also
driven mechanically by the diesel engine or the energy source 36.
The converter module 44 comprises an electric machine, which
operates as a generator and which generates electric alternating
current when the diesel engine is operating. The generated
alternating current is first converted into direct current by a
rectifier unit allocated to the converter module 44 (and not shown
in FIG. 2) and fed to the two drive modules 12, 14 via the input
interface 38 with the aid of the connection line 46 via the
controller 16. The two drive modules 12, 14 are electric machines,
which are constructed in the form of motors and which each has a
rectifier unit (not shown in FIG. 2) with which the direct current
is converted into alternating current. The controller 16 comprises
power electronics, which enables it to feed electric current merely
to the first and/or to the second drive module 12, 14, so that also
in this embodiment, the two drive modules 12, 14 can each drive the
first and/or the second branch 22, 24 continuously and
independently of each other and thus--analogous to the functioning
in the embodiment from FIG. 1--also the drive interface 30.
[0058] FIG. 3 shows a third embodiment of the present invention,
wherein the drive system 10 according to the invention can be
connected at its input interface 38 to a energy source 36
constructed in the form of a diesel engine. In this embodiment, the
energy source 36 is mechanically coupled to the second branch 24.
The first branch 22 is non-mechanically coupled to the energy
source 36. The converter module 44, which is constructed in the
form of an electric machine embodied as a generator, is always
coupled to and driven with the second branch 24. The electric
current generated by the converter module 44 is fed via the
connection line 46 to the controller 16, which on its side can
temporarily store the electric current in a buffer (not shown in
FIG. 3); for example, in a capacitor or accumulator. On the one
hand, the second drive module 14 can be driven via connection line
20 and, on the other hand, the first drive module 12 can be driven
via connection line 18.
[0059] The first branch 22 can be driven only by the first drive
module 12 via the gear connection 26. The first branch 22 can be
connected to the output interface 30 via the two meshing spur gears
48, 50, as long as the shift point 52 creates a rotationally locked
connection between the output interface 30 constructed in the form
of a shaft and the spur gear 50. The second drive module 14 can be
connected to the second branch 24 via a shaft 53 via a gear stage
54 constructed in the form of a planetary gear. In this respect, it
is conceivable that the mechanical torque generated by the energy
source 36 is transmitted to the output interface 30 via the shafts
56, 58, and also via the two spur gears 60, 62, as long as the
shift point 64 creates a rotationally locked connection between the
spur gear 62 and the output interface 30.
[0060] However, it would also be conceivable for the shaft 56 to be
decoupled from the shaft 58 and the drive module 14 to be connected
to the shaft 58. In this case, the electric current generated by
the converter module 44 is led by means of the controller 16 to the
drive module 14, which drives the shaft 53, so that the mechanical
torque generated by the drive module 14 is transmitted to the
output interface 30 via the gear stage 54, the shaft 58, the two
spur gears 60, 62, and the closed shift point 64. Finally, a shift
state for the second branch 24 is also conceivable, in which, via
gear stage 54, mechanical torque is transmitted as a sum to the
shaft 58 both from the shaft 56 and also from the shaft 53, so
that, on the one hand, the torque generated by the energy source 36
can be transmitted and, on the other hand with the mechanical
torque generated by the second drive module 14 can be ultimately
transmitted to the output interface 30. In this shift state, the
shafts 56, 53, and 58 are coupled to each other via the gear stage
54.
[0061] The drive system 10 from FIG. 3 comprises a second output
interface 66, which is locked in rotation via the shift point 70
via a spur gear 68 meshing with the spur gear 60. The second output
interface 66 could be, for example, a power take-off of a tractor,
which is equipped with a drive system 10. A brake 71, with which
the shaft 58 and the corresponding part of the gear stage 54 can be
stopped relative to a housing of the drive system 10 (not shown in
FIG. 3), is provided for the shaft 58. If the brake 71 is engaged,
not only the converter module 44, but also the second drive module
14 is driven by the energy source 36. In this mode, the second
drive module 14 is operated as a generator, so that both the
converter module 44 and also the second drive module 14 can each
generate electric current and the first drive module 12 or an
electrical on-board distribution system (not shown in FIG. 3) can
be made available.
[0062] FIG. 4 shows a fourth embodiment of the present invention.
Here, the drive system 10 can be connected to an electrical energy
source 36 via the input interface 38, wherein the energy source 36
could be a generator driven by an internal combustion engine or a
fuel cell. The electrical energy generated by the energy source 36
is fed to the controllers with rectifier units 74 or 76 of the two
drive modules 12, 14 via the connection lines 72.
[0063] The electrical energy could involve direct current. However,
if the energy source 36 has a generator driven by an internal
combustion engine, this engine typically delivers alternating or
rotating current at a frequency dependent on its rotational speed.
Because the drive modules 12, 14 were to be operated at a
constantly changing frequency, the drive modules 12, 14 could
output an arbitrary given power, although not unlimited. Therefore,
the alternating or rotating current is first converted into direct
current with the aid of a rectifier unit not shown in the figures,
before it is fed to the controllers 74, 76. The electrical energy
converted into direct current is converted back into alternating
current at a given frequency, in this case with the aid of another
rectifier unit allocated to each controller 74, 76, in order to
finally drive the drive modules 12, 14 constructed in the form of
electric motors. The drive modules 12, 14 each drive the first or
second branch 22, 24. The first branch 22 can be connected to the
output interface 30, on the one hand with the aid of the two spur
gears 48, 50 via the shift point 52. On the other hand, the first
branch 22 can be connected to the output interface 30 via the spur
gears 78, 80 and the shift point 82. The second branch 24 can be
connected to the output interface 30 via the spur gears 60, 62 and
the shift point 64. Furthermore, the second branch 24 can be
connected to the output interface 30 via the spur gears 84, 86 and
the shift point 88. Depending on the shift points 64, 88, 52, and
82, the first branch 22 and/or the second branch 24 can be
reversibly connected to the output interface 30. The second branch
24 can be reversibly connected to the second output interface 66
via the shift point 90 and the spur gears 92, 94.
[0064] The drive system 10 shown in FIG. 4 is provided in an
especially preferred way for a tractor and designed or configured
such that it is distinguished by at least four travel ranges. In a
first travel range, the shift point 52 is coupled so that the drive
module 12 is locked in rotation with the output interface 30 via
the spur gears 48, 50, wherein the output interface 30 is connected
to a traction drive in a tractor. By changing the rotational speed
and reversing the direction of rotation of the drive module 12, the
traveling speed of the tractor can be changed or the direction of
travel can be reversed. Operating the other output interface 66 in
this travel range is possible via the second branch 24, wherein the
output interface 66 is connected to a power take-off in a
tractor.
[0065] In a second travel range, the shift points 52 and 64 are
coupled or closed simultaneously so that the drive module 12 is
locked in rotation via the spur gears 48, 50 and the drive module
14 is locked in rotation via the control line 60, 62 to the output
interface 30 and thus to the traction drive of the tractor. Here,
the drive power of the two drive modules 12, 14 combine, so that
for the same traveling speed of the tractor, a higher traction
force and a higher power are made available. In this shift state,
operation of the other output interface 66 is not possible or
possible only to a limited extent. The traveling speed in the first
and in the second traveling range is limited by the highest
permissible rotational speed of the drive module 12.
[0066] In a third traveling range of the tractor, the shift point
64 is closed, so that the second drive module 14 is connected via
the spur gears 60, 62 to the output interface 30. In a useful
design of the drive system 10 according to the invention, the
traveling speed is significantly higher in this third traveling
range and the traction forces are significantly lower than in the
first traveling range, so that an expansion of the spread is
achieved.
[0067] A transition from the first to the second traveling range
and back can take place by closing or opening the shift point 64 at
a synchronized rotational speed between the drive interface 30 and
the spur gear 62 and without changing the torque flow in the
traction drive and thus it is also unnoticed by the driver.
[0068] A transition from the second to the third traveling range
and back can take place by opening or closing the shift point 52 at
a synchronized rotation speed between the drive interface 30 and
the end wheel 50 and without changing the torque flow in the
traction drive and thus it is also unnoticed by the driver as
well.
[0069] In the first traveling range of the tractor, the second
drive module 14 is not used for the traction drive. Therefore, it
can be locked in rotation by means of the shift point 90 to the
other output interface 66, i.e., the power take-off of the tractor.
By changing the rotational speed of the second drive module 14, the
rotational speed of the other output interface 66 can change
continuously. It then corresponds to its function of a modern
"motor power take-off."
[0070] Also in the second and third traveling range, the shift
point 90 can be closed and thus the other output interface 66 can
be driven. The power take-off rotational speed then changes in
proportion to the traveling speed. The power take-off thus
corresponds to its function of a modern "motion power
take-off."
[0071] In principle, it is possible to increase the number of
traveling ranges through other transmission stages and shift
elements arbitrarily and/or to increase the necessary spread of the
drive system 10 according to the invention and/or to reduce the
necessary spread of the two drive modules 12, 14, without losing
the advantages of synchronous, no-load shifting. A fourth traveling
range is produced by simultaneously closing of the shift points 64
and 82, a fifth traveling range is produced by closing only the
shift point 82, a sixth traveling range is produced by closing the
shift points 88 and 82, and a seventh traveling range is produced
by closing just the shift point 88. In the traveling ranges two,
four, and six, the traction drive power is transmitted from the two
drive modules 12, 14, so that a higher power is made available than
in the ranges one, three, and five. For suitable selection of the
transmission ratios, it is possible to cover the entire range of
speeds of a tractor with the ranges with simultaneous power
transfer, so that traveling can preferably be performed in these
ranges. It is then also possible to design the two drive modules
12, 14 not for the entire drive power of the tractor.
[0072] By simultaneously closing two suitable shift points, the
traction drive can be blocked, and thus a function of a parking
brake device can be achieved. In the embodiment from FIG. 4, these
could be, for example, the shift points 52 and 82 or 64 and 88.
Thus, the embodiment of a drive system 10 according to the
invention sketched in FIG. 4 is distinguished by a uniform design
for the traveling and power take-off mode. A good use of
installation space can be achieved. The drive modules 12, 14
constructed in the form of electric machines can have a smaller
size than the machines typically used from the state of the art.
High traction forces can also be achieved for low traveling speeds
without over-dimensioning the two drive modules 12, 14 through
parallel connection of the two drive modules 12, 14. Especially
advantageously, a shifting process can take place at a synchronized
rotational speed via another range, wherein a torque-free or
jerk-free shifting is possible.
[0073] FIG. 5 shows a fifth embodiment of a drive system 10
according to the invention, which is similar to the embodiment from
FIG. 3, also in its functioning, and where equivalent or similar
components are represented by the same reference symbols. Thus, the
first branch 22 of the drive system 10 includes, in addition to the
first drive module 12, essentially a hollow shaft 96, which is
locked in rotation with the spur gear 48. The spur gear 48 meshes
with the spur gear 50, which can be connected reversibly to the
first output interface 30 via the shift point 52. The second branch
24 includes, on the one hand, the shaft 56, which is driven by the
energy source 36 constructed in the form of a diesel engine. The
second branch 24 further includes the converter module 44, which is
always driven by the diesel engine 36. The second branch 24 further
includes a hollow shaft 53, which is locked in rotation with the
rotor of the second drive module 14 constructed in the form of an
electric machine. The shaft 56 and the hollow shaft 53 are
connected to the planetary gear 54, wherein the planetary gear is
further connected to the shaft 58. The second branch 24 further
includes the brake 71, with which the shaft 58 and a part of the
planetary gear 54 can be stopped, as well as the spur gears 98, 100
meshing with this gear, and also the two spur gears 60, 62 meshing
with each other. The shaft 102 rotationally locks the two spur
gears 100, 60 to each other. The spur gear 62 of the second branch
24 can be connected to the shift point 64 reversibly to the output
interface 30. The second branch 24 can be further connected
reversibly to the second output interface 66 via the spur gear 68
meshing with the spur gear 98 via the shift point 70.
[0074] In this embodiment, the output interface 30 is also
connected to the traction drive of a tractor not shown in FIG. 5
and also the output interface 66 is connected to the power take-off
of a tractor similarly not shown in FIG. 5. The converter module 44
and also the first and the second drive module 12, 14 are connected
via connection lines and each to a frequency converter 104, 106,
and 108. The controller 16 is connected to each frequency converter
104, 106, 108. Thus, the converter module 44 can be operated by the
controller 16 and the frequency converter 104 in one direction of
rotation--namely, that of the diesel engine 36--and in two torque
directions for braking or accelerating. The drive modules 12, 14
can be operated by the controller 16 and each frequency converter
106, 108 in two directions of rotation and in two torque directions
for braking or accelerating.
[0075] The controller 16 is connected to sensors (not shown in FIG.
5) and a data interface for vehicle-relevant information of the
operating state of the diesel engine 36. It also receives the
rotational speed of the other output interface 66, wheel or axle
rotational speeds, which are detected by corresponding sensors (not
shown in FIG. 5) and which are made available to the controller 16.
In this respect, the controller 16 shown in FIG. 5 acts as a higher
order controller of a vehicle equipped with the drive system 10
according to the invention and also takes over the energy
management of the vehicle, as well as the power supply for other
electric loads (also not shown).
[0076] The embodiment according to FIG. 5 also includes a first
traveling range in which the other output interface 66 is not
activated. Here, the shift point 52 is coupled so that the spur
gears 48, 50 are locked in rotation with the output interface 30,
and thus the first branch 22 is driven by the first drive module
12. The brake 71 constructed in the form of a friction brake is
here closed so that the converter module 44 and the second drive
module 14 operating as a generator are driven by the diesel engine
36, and the electrical power generated in this way is made
available to the first drive module 12 operating as a motor. By
changing the rotational speed and reversing the direction of
rotation of the first drive module 12, the traveling speed of the
vehicle can be changed and the traveling direction reversed.
[0077] The brake 71 is opened in a second traveling range. The
rotational speed of the diesel engine 36 and the rotational speed
of the second drive module 14 combine in the planetary gear 54. The
interface 64 for a synchronized rotational speed can be connected
to the spur gear 50 via the shaft 58, the spur gears 98, 100, the
shaft 102, the spur gears 60 and 62. In the second traveling range,
it is not possible to use the other output interface 66. The shift
point between the branches 22, 24 must not be realized at a
discrete rotational speed. Depending on the design of the
components, there is a certain overlapping range of rotational
speeds of the direct and power-diverted paths. Here, in an
especially advantageous way, a comfortable and efficient shifting
process is enabled.
[0078] Instead of shifting from the first to the second traveling
range, the other output interface 66--and thus for a tractor, the
power take-off--can also be activated. Here, the shift point 64 is
opened and the shift point 70 is closed. The brake 71 is opened and
power can be taken at the other output interface 66.
[0079] The rotational speed of the diesel engine 36 can be freely
selected within limits according to power requirements. The control
of the diesel engine 36 as well as the control of the converter
module 44 and the first and second drive module 12, 14 can be
realized, such that an optimal objective stored in a higher-order
controller--e.g., in the controller 16--is rejected. The optimal
objective can be, for example, lower fuel consumption or the lowest
possible noise production. The design of this embodiment combines a
continuous traction drive with a continuous power take-off
Therefore, in a conventional tractor equipped with the drive system
10 according to the invention, the two installation spaces
typically provided for these components is available for use.
[0080] The converter module 44 and the first and second drive
modules 12, 14 form the electric drive part of the drive system 10
shown in FIG. 5. They are combined together compactly downstream of
the diesel engine 36 and can thus be installed in an optimal
environment for electric machines, for example, no oil in the gear
and stators water-cooled from the outside. For the installation of
the drive system 10 according to the invention from FIG. 5 in a
tractor, the shift points 52, 64 and also the spur gears 48, 50,
60, 62 can also be located in front of the differential housing.
The planetary gear 54, the brake 71, and also the spur gears 68,
98, 100 could be housed in the installation space of the power
take-off.
[0081] Other variations for this embodiment are conceivable. Thus,
for example, for shifting to the second traveling range, a power
shift coupling can be used. The second branch 24 and/or the second
output interface 66 could also have a direct, instead of
power-diverted, configuration. The shift point 70 could have
another transmission ratio. An electric front-wheel drive can
replace a mechanical front-wheel drive. An electrically driven
front axle with one or two electric machines can replace one
conventional front-wheel drive.
[0082] Finally, it should be specifically mentioned that the
previously explained embodiments are used merely for describing the
claimed teaching, but this is not limited to the embodiments.
* * * * *